1. Field of the Invention
The present invention relates to an information management apparatus which forms part of a client-server data communication network, and which enables a plurality of multimedia titles to be shared by the client terminals and server computers of such a system. In particular the present invention relates to an information management apparatus whereby various types of monomedia data constituting the subject matter data of a multimedia title are stored in respectively different data storage devices.
The term "multimedia title" as used herein signifies a multimedia object which consists of a plurality of sets of subject matter data of respective monomedia objects (i.e. respective sets of data expressing video clips, audio clips, still pictures, text items, etc.) in conjunction with scenario data. The scenario data specify the storage locations of respective data files containing the subject matter data and also specify how the subject matter data are to be presented during playing of the multimedia title, i.e. times of starting and ending presentation of respective items, display screen window sizes and positions for respective items, etc. The term "management" of multimedia titles as used herein basically signifies such processing as registering new multimedia titles in response to requests and data supplied from client terminals, supplying specific data contents of a multimedia title or information relating to the title, in response to a request from a client terminal, deletion of data relating to a multimedia title from storage, when necessary, etc.
2. Description of the Prior Art
In the following, it will be assumed that a client-server network system has a specific server computer which functions as an information management servers for managing data of multimedia titles, and that each of the client terminals communicate mutually independently with that information management server. In practice, the client terminals may also be able to access other server computer systems via the network.
In a prior art client/server network, a user of a client terminal, which in general will be a usual type of personal computer having limited data storage resources, can create a new multimedia title by using the high-capacity data storage devices of the server computer (which will typically be a work station) to store the data of the multimedia title, i.e. high-capacity data storage devices such as hard disk units, which are shared by the server computer and all of the client terminals of the network. The process of creating a multimedia title is illustrated in the conceptual diagram of FIG. 2. The first stage is inputting of subject matter data (which can be used as a basis for creating the multimedia title, i.e. basic subject matter data) by the user, using a client terminal. As the second stage, these basic subject matter data are transferred to the server computer, to be stored in data storage devices of the server computer, i.e. in data storage which is shared by the server computer and each of the client terminals of the network.
In the third stage, the user of the client terminal selects desired parts of the stored basic subject matter data, i.e. those parts which are to be actually used in the multimedia title, and generates the part of the scenario data which constitutes the "story" of the multimedia title, i.e. the scenario. These data specify, for respective time points during playing of the multimedia title, presentation of respective monomedia objects of the multimedia title, i.e. specify those points at which respective sets of subject matter data must be obtained from storage and used to generate a video picture, still picture, audible item, etc., during a specific interval, and also specify how such items are to be presented (i.e. display window position, size, etc.), as well as respective time points at which presentation of the items is to be ended. In addition, a list of the selected subject matter data (i.e. specified as respective data files) and storage location information for the subject matter data, are also generated. That third step will be referred to in the following as "authoring".
In the fourth step, which constitutes the title registration processing, in the prior art, the subject matter data file information and the scenario information generated by the authoring stage are supplied to the server computer, which then generates a scenario file. This includes respective storage location information for the subject matter data files, and the "story" information, i.e. sequence of events, linked to the subject matter data files.
The purpose of the title registration processing is to enable the multimedia title to be managed as an integrated set of data, or more specifically, as an integrated set of data files. One aspect of this is that all of the multimedia title data (subject matter data files and scenario file) are stored in the same data storage installation, i.e. at the server computer which is responsible for multimedia title management. Another aspect is that these multimedia title data must be stored such as to be directly accessible by the server computer and also (at least with respect to read-out operations) by all of the client terminals of the network. One reason for this is that, when the server computer receives a request from a client terminal for the data of a specific multimedia title, the server computer must then read out and transfer the scenario file of that multimedia title to the requesting client terminal. That client terminal must be able to then directly access and read out all of the subject matter data files whose names and storage location information are specified in the scenario file.
In addition, to enable such management of the multimedia title, it must be possible for the "story" part of the scenario to be correctly linked, in the scenario file, to the actual storage locations of the respective subject matter data files, as a result of the title registration processing.
However with such a prior art type of information management apparatus used for creating and managing multimedia titles, the problem may arise that the computer which constitutes a client terminal may use a different format for expressing data storage locations from that used by the computer which constitutes the server, since these computers may utilize different types of basic operating software, i.e. different operating systems.. This is conceptually illustrated in FIG. 3, in which a file having the name "data.mpeg" (such as a file containing compressed video data) is held in a storage device of a server computer, which is used in common by the server computer and one or more client terminals. In this example, the server computer expresses the storage location information for the file "data.mpeg" as: EQU //server/data/video/data.mpeg
This is an absolute path name, i.e. leading from the root of the file directory structure of the server computer.
However the operating system of the client terminal (i.e. internally, with respect to handling file access requests from a user and presenting file storage location information to the user) might express the contents of the directory "/data" of the server as if these were stored on a (virtual) local disk drive of the client terminal, identified by a "drive letter". In that case the storage location designation employed by the user of the client terminal (i.e. in communicating with the client terminal), for that same file, might be: EQU F:/VIDEO/MPEG/DATA.MPG
This represents a relative path name, leading from the "/data" directory of the server file system. Such storage location information cannot be used directly by the server computer to access files.
In addition, client terminals may use various different types of path name delimiter. For example, the above example might be expressed within the file system of the client terminal as: EQU F:.Yen.VIDEO.Yen.MPEG.Yen.DATA.MPG
In the following, all of such differences in modes of expressing the same data file storage location information by different computer systems will be referred to collectively as differences in storage location information syntax.
In the case of creating and registering a multimedia title, this can lead to a serious problem, since the server computer which is to manage the multimedia titles must obtain the storage information for the subject matter data from a scenario file prepared by the user, which is a text file. That is to say, if a user of the client terminal shown in FIG. 3 prepares the contents of the scenario for a new multimedia title as described above, i.e. consisting of the "story" data for a multimedia title and information specifying the storage locations of the subject matter data of that multimedia title expressed in the syntax used within the operating environment of that particular client terminal, and sends to the server computer a scenario file which includes such storage location information, then the server computer will not be able to correctly use that information. For that reason, it has been necessary in the prior art to use a temporary data storage device (i.e. controlled by a local computer), which is connected via the nework to the server computer and each of the client terminals, and can be directly accessed by the server computer. When a new multimedia title is being created, the client terminal user selects required subject matter data files and causes (i.e. using the particular method of storage location information designation which is employed with that client terminal) the selected files to be read out of the aforementioned common data storage device of the server computer, and transferred via the network to be stored as respective files in the temporary data storage device. When a subject matter data file has been stored in that device, it can be accessed by the server computer, and its contents transferred via the network to be stored in the common data storage device. When all of the subject matter data files have been transferred in that way to the server computer, the title registration processing can begin.
That is to say, in this case, since the temporary data storage device and the computer which controls operation of the temporary data storage device are fixed, the path to any specific storage location within that temporary data storage device is fixed. Hence, it becomes possible for the server computer to access a file which is held in the temporary data storage device by using only the file name, i.e. without it being necessary to specify a computer name or directory name.
However if the subject matter data include very large amounts of data, such as extensive video data files, then a considerable time is required to transfer data between storage devices via the network, so that an excessive amount of processing time is required to complete the registration processing for a multimedia title.
There is therefore a requirement for an information management apparatus which would enable a server computer to directly access subject matter data files whose storage location information have been generated by a client terminal, for thereby increasing the speed and efficiency of title registration processing and of the management of multimedia titles by the server computer.
Another problem which arises is that, with such a client-server system used as an information management apparatus for registering and managing multimedia titles, the various client terminals may use respectively different application programs for preparing the scenarios, so that the structures of the resultant scenarios will not be uniform, between the various client terminals. For example, some client terminals may use a single-file structure, others may use a dual-file structure, i.e. a header file which contains only subject matter data file names and storage location information, together with a scenario file which contains the actual "story" of the multimedia title, i.e. which relates successive events of the title to specific subject matter data files, etc.
Also, with a multimedia title, the respective storage locations of the various sets of monomedia data (i.e. data files expressing video clips, audio clips, text items, etc) which constitute the contents of the title are listed only within the scenario file of that multimedia title, and so are not directly accessible. That is to say, if a user of a client terminal wishes to access a subject matter data file of a multimedia title which is stored in a server computer, then it is necessary for that user to first execute operations to acquire the scenario file of that multimedia title from the server computer, then examine the contents of the scenario file to find the storage location of the desired subject matter data file. However in a client-server system, the various client terminals may have different types of operating system from one another. As a result, when the client terminals are used to create multimedia titles, the syntax used in the resultant scenarios, e.g. to express file storage locations (i.e. path names) may be respectively different between the various client terminals, as well as between the client terminals and the server.
In a client-server nework system in which it is desired to enhance productivity by making as many resources and data available to be shared by all of the users of the client terminals, it would be desirable for not only complete multimedia titles to be freely available to all of the client terminals, but also for the respective subject matter data of these multimedia titles to be similarly freely accessible from each client terminal. In that case, for example, it becomes possible for users to extract desired subject matter data files from a pre-existing multimedia title, to insert some or all of the contents into a multimedia title which is being newly created, thereby increasing productivity. However because of the problems of difficulty of direct access to subject matter data files and differences between command formats of client terminals which employ computers having various different types of operating system, etc, it has not been possible to provide such free access to the multimedia title subject matter data, in the prior art.
Furthermore in recent years, the scope of computer networks has extended to a worldwide scale, as is exemplified by the Internet. In such networks, the HTML (Hypertext Markup Language) is generally used to express data in a form which can be easily and rapidly searched for and located, e.g. as items contained in respective menu (notice board) pages which are successively linked. The HTML standards are defined in detail in an Internet Draft of the IETF (Hypertext Markup Language--2.0) Mar. 3, 1995, MIT/W3C, so that detailed description will be omitted.
However in the prior art, it has been difficult to use a standard technique for rapid look-up of data, such as HTML, to access stored multimedia titles. This is basically due to the tact that in order to access a multimedia title which is stored at a server computer, it is necessary to supply to the server computer (e.g. from a client terminal) commands which are in the specific format which will be recognized by the server computer.